On Thu, 2003-09-11 at 08:54, Arne Gehlhaar wrote:
Kevin,
you are not using file devices on a ReiserFS partition as database devices, are you? As you probably know, ReiserFS is a journaling filesystem, meaning every access to the fs is logged in a journal, which leads to a whole lot of extra i/o on your disk => not a very good idea for database devices (volumes). Use raw devices instead.
Please have a look at this oracle 8i benchmark :
http://otn.oracle.com/oramag/webcolumns/2003/techarticles/scalzo_linux02.html
It clearly prooves you wrong as ext3 is the fastest performing fs on this test, and raw devices is clearly a bad choice under linux.
...but still better that ReiserFS.
But I don't think this article is very helpful. First of all it deals with Oracle, not SAPDB. So you know how well Oracle deals with raw devices on Linux but nothing more.
Secondly when it comes to data loss, I don't know how reliable a database volume sitting on top of a file system sitting on top of a logical volume manager sitting on top of a raid array sitting on top of a number of disks actually is. Of course a filesystem which uses read and write caches is faster than a raw device but caches are volatile which is what you don't want on a database device, at least I don't...
I'd like to know the performance of ext3 with its caches turned off!
Arne
-- Institute of Shipping Economics and Logistics http://www.isl.org/ Arne Gehlhaar mailto:[EMAIL PROTECTED] Universitaetsallee GW1 Block A phone:+49.421.22096.49 D-28359 Bremen, Germany fax:+49.421.22096.55
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